Whey proteins of the common brushtail possum (Trichosurus vulpecula): isolation, characterization and changes in concentration in milk during lactation of transferrin, alpha-lactalbumin and serum albumin.

1. Transferrin and serum albumin were purified from both whey and serum and alpha-lactalbumin was purified from whey from the common brushtail possum (Trichosurus vulpecula). 2. The N-terminal amino acid sequences for transferrin and serum albumin were identical for the proteins from both whey and serum and showed homologies with transferrin or serum albumin from other species. 3. N- and C-terminal regions of possum alpha-lactalbumin were also sequenced and have been compared with wallaby alpha-lactalbumin and several eutherian alpha-lactalbumins. 4. Antisera raised to each of the three proteins were species specific and Western blots further confirmed the identity of the serum and whey transferrins and serum and whey serum albumins. 5. The concentration of transferrin increased ten-fold between days 110 and 130 of lactation, whereas no significant changes in the concentration of alpha-lactalbumin could be detected after day 60.